Problem if you only have the 75 Ohm input on the TV, is that you have to 're-modulate' the output signal from your laptop.
So you need something like this ;
RF Modulator
- coupled with an S-Video lead which will split out the video and audio from your laptop to phono connectors for the inputs to the above box.
I'm not expert but just my tuppence worth.
Someone will no doubt shoot me down in flames !!
Another thought would be to go for the S-Video to SCART adapter you have already found.
Connect that to a video or digibox with a SCART
input and coax output, the video/digibox may do the RF modulation for you without the need for a seperate modulator.
Not sure if that would work - hence the emphasis on SCART input.